DESCRIPTION: This is a Fogarty-NIH proposal which seeks funding for a study of two-component signal transduction proteins from the human pathogenic fungus, Aspergillus fumigatus. The parent grant is entitled, "The response regulator gene (CaSSK1) of Candida albicans, 1 R0l A147047-01. The study will be performed in the laboratories of Drs. Calderone (PI) and Latge (foreign collaborator). Dr. Latge's lab has made numerous contributions to our understanding of the pathogenesis of aspergillosis through both biochemical and molecular approaches. Dr. Calderone's lab has focused their research on the 2-component histidine kinases and the response regulator signal proteins of Candida albicans. He has shown that these proteins (Chk1p and Csk1p) are required for the formation of hyphae and the regulation of a hyphal cell surface protein. Strains deleted in their encoding genes are also avirulent. The long-term objective of this research is to establish the importance of these proteins in the growth and virulence of A. fumigatus. The hypothesis of this proposal is that regulation of growth and virulence in this organism is achieved through 2-component signaling. In other systems, 2-component signaling is required for the expression of multiple virulence factors. Thus, studies of signal pathways in this organism may reveal more about virulence factors than construction of a strain with a single-gene disruption. The specific aims of the proposal include: 1) genes encoding the homologs of the C. albicans Chk1p and Cssk1p are to be cloned and characterized. 2) Strains of A. fumigatus deleted in each of these genes will be constructed and their phenotypes characterized in vitro. 3) The gene deleted strains will be evaluated in an intranasal model of murine invasive aspergillosis. If determined to be important to this organism, our studies may suggest that 2-component proteins are relevant targets for the development of broad-spectrum antifungals.